1. Field of the Invention
The present invention relates to assembleable and disassembleable frame structures such as used for scaffolding, shelving, conduits, structural supports, railings and the like, and more particularly relates to such structures which utilize junction elements and compound tube components enabling relatively stronger spans and relatively simpler construction than is possible with conventional single tube components.
2. Description of the Prior Art
Conventional frame structures of a readily assembleable and disassembleable nature are commonly made up of cylindrical tubing and various types of junction elements or connectors, or so-called slip fit or slip-on fittings, commonly termed corner, ridge intermediate, intermediate, three-way crown, four-way crown, six-way crown and eight-way crown fittings, fabricated of aluminum or steel tubing. Conventionally, also, the tubes and fittings are joined together in a telescoping manner with the tubes telescoped over associated arms of the fittings and the tubes and fittings are interlocked together by so-called locking quick pins. However, when sturdy structures are desired of relatively strong characteristics, the assemblage becomes quite complicated with need oftentimes for additional internally placed supporting components.
Crow U.S. Pat. No. 1,958,296 discloses tent frames providing an increased span between corner posts by use of arched braces, also called trusses, which in general are made up of laterally spaced top and bottom chords interconnected by spaced struts.
In general it is also known as in Dithridge U.S. Pat. No. 426,558 to construct "beams or sills for railway-cars" with tubular edges and with one or more connecting plates therebetween and with one or more connecting plates arranged essentially coplanar with the axial centers of the tubular edges, but without any suggestion of utilization of any similar compound tubular configuration in readily assembleable and disassembleable structures such as the structures to which the present invention applies.